Pretreatment enzymatic activity

Data received from three laboratories were excluded from the statistical analysis because all three reported low enzymatic activity (< 50% of the expected values), due to procedural errors. For example, laboratory J performed sample pretreatment over a period of 4 days and assayed for activity during the fifth day, this caused significant loss of enzymatic activity. Two laboratories did not return results. Statistical analyses were conducted using the data produced by the remaining participants results are shown in Table 16.6. 

The use of antibody- or aptamer-based approaches to protect against ricin holds potential as a possible pretreatment for armed forces, or as an adjunct to PPE for civilian first-responders and other special populations required to enter contaminated areas. However, extracellular antitoxin would probably be of limited use in a bioterrorist or civilian mass casualty scenario, because the therapeutic window for administration is likely to be short (a few hours), the delay to onset of symptoms is relatively long, and there presently is no method of immediately detecting ricin exposure. It also remains to be determined whether specific combinations of MAbs are required for optimal in vivo protection against the toxin. Moreover, in some cases, MAbs that bind toxin with high avidity and block enzymatic activity of RTA in vitro actually enhance the toxicity of ricin in vivo (Maddaloni et al., 2004). 

Pretreated (enzymatic and enzymatic-I-hydrogen peroxide) knitted wool fabrics were treated with argon and atmospheric air plasma to improve adsorption capacity (Demir et al., 2010). After plasma treatment, a chitosan solution was appUed for antimicrobial effect. The treated fabrics were evaluated in terms of washing stabiUty as well as antimicrobial activity. The surface morphology was characterized by SEM images and Fourier transform infrared (FilR) analysis. The results indicate that the atmospheric plasma treatment had an etching effect and increased the fiinctionahty of wool surface. Atmospheric plasma treatment also enhanced the adhesion of chitosan to the surface and improved the antimicrobial activity. 

Melanoma can be diagnosed throngh the monitoring of tyrosinase, a cytoplasmic melanocyte differentiation protein, which is a key enzyme in melanin synthesis and has been listed as important melanoma biomarker. Mossberg et al. (2014) developed an electrochemical biosensor platform with an amperometric detection mode to detect the enzymatic activity of tyrosinase in fresh biopsy samples withont pretreatment of the samples. The combination of this method with modem portable devices can provide interesting POC sensors in the fnture. 

Unfortimately. the interpretation of the spectral changes may be obscured by a number of other factors. (1) The magnitude and even the apparent type of spectral change may be affected by the presence of endogenous substances which are displaced by drug substrate in microsomes from animals pretreated with 3-methylcholanthrene. the spectral changes caused by type I substances may be diminished or appear to be atypical type II presumably because the type I sites are occupied by a metabolite of 3-methylcholanthiene. (2) A substance may be bound to a number of different sites not all of which are enzymatically active in fact, liver microsomes contain considerable amounts of a cytochrome P-450 species which is reduced very slowly by NADPH. (3) A substance may be bound to a number of different forms of cytochrome P-450. but these forms may catalyse different reactions or proceed at markedly different rates. In any event, studies based solely on spectral changes must be interpreted with caution. 

The effect of enzymatic demethylation of G-pectin on the activity of PAE, PG and PL (left) The effect of pretreatment of G-pectin with PL on the activity of PAE (right)... 

Antioxidant activity was also tested in a liver microsome system. In this study, mice were treated by oral intubation (2 times/wk) with 0.2 ml olive oil alone or containing CLA (0.1 ml), linoleic acid (0.1 ml), or dl-a-tocopherol (lOmg). Four weeks after the first treatment, liver microsomes were prepared and subsequently subjected to oxidative stress using a non-enzymatic iron-dependent lipid peroxidation system. Microsomal lipid peroxidation was measured as thiobarbituric acid-reactive substance (TBARS) production using malondialdehyde as the standard. It was found that pretreatment of mice with CLA or dl-a-tocopherol significantly decreased TBARS formation in mouse liver microsomes (p < 0.05) (Sword, J. T. and M. W. Pariza, University of Wisconsin, unpublished data). 

Although most cellulase enzyme complexes, including Celluclast, contain xylanase activity (data not shown), the amount of released xylose after enzymatic hydrolysis was negligible, especially compared with the amount of released xylose after pretreatment. 

Furthermore, enzymatic hydrolysis of the corn stover treated under optimal AFEX conditions showed almost 98% glucan conversion and 80% xylan conversion vs 29 and 16% for untreated com stover, respectively (at an enzyme loading of 60 FPU/g of glucan). Unlike acidic pretreatments, AFEX does not generate sugar monomers. The cellulase mixture in our study was developed for hydrolysis of acid-pretreated materials and has about 1% by weight xylanase activity (J. Cherry, personal communication, Nov. 2002). Enzyme cocktails with enhanced xylanase activity would presumably completely hydrolyze AFEX-treated xylans. 

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